There is disclosed herein an imaging member used in electrophotography having a charge transport layer with multiple regions. More particularly, disclosed herein is an imaging member that has a photogenerating layer and a charge transport layer comprising a plurality of charge transport layers or sub-layers coated from solutions of similar or different compositions and/or concentrations to form two or more distinctive, but contiguous solid solution coating layers. In the resulting imaging member, the first (bottom) charge transport layer comprises a higher concentration of charge transport materials in a solid solution than the additional or upper charge transport layers.
An electrophotographic imaging member device comprising at least one photoconductive insulating layer is imaged by uniformly depositing an electrostatic charge on the imaging surface of the electrophotographic imaging member and then exposing the imaging member to a pattern of activating electromagnetic radiation, such as, light which selectively dissipates the charge in the illuminated areas of the imaging member while leaving behind an electrostatic latent image in the non-illuminated areas. This electrostatic latent image may then be developed to form a visible image by depositing finely divided electroscopic marking toner particles on the imaging member surface. The resulting visible toner image can then be transferred to a suitable receiving member such as paper.
A number of current electrophotographic imaging members are, for example multilayered photoreceptors that, in a negative charging system, comprise a substrate support, an electrically conductive layer, an optional charge or hole blocking layer, an optional adhesive layer, a charge generating layer, a charge transport layer, and optional protective or overcoating layer(s). The imaging members of multilayered photoreceptors can take several forms, for example, flexible belts, rigid drums, flexible scrolls, etc. Flexible photoreceptor belts may either be seamed or seamless belts. In a typical flexible photoreceptor belt design, an anti-curl layer may, for example, also be employed on the back side of the flexible substrate support, the side opposite to the electrically active layers, to achieve the desired photoreceptor belt flatness.
Multilayered photoreceptors, when functioning under electro-photographic machine service conditions, do exhibit typical mechanical failures such as frictional abrasion, wear, and surface cracking. Surface cracking frequently seen in belt photoreceptors is induced either due to dynamic fatigue of the belt flexing over the supporting rollers of a machine belt support module or caused by exposure to airborne chemical contaminants such as solvent vapors and corona species emitted by machine charging subsystems while the photoreceptor belt is subjected to bending stress. In fact, photoreceptor surface cracking is one of the common and most urgent mechanical problems seen, particularly, in flexible belts. This problem requires quick resolution, because the cracks so generated produce printout defects that seriously impact copy quality.